Here you go. As you can see it could be a bit sharper, but it was quite far away.
Steps taken: Converted the rawfile to tiff, no sharpening or anything. Cropped it, saved it as tiff, again nothing else.
Imageshack made a png of it.

Exif: f/18, 1/25 sec @ ISO 100

Not posting much here anymore, but the photo's you can follow here There is plenty there.

Feel free to use any of these additional letters to correct the spelling of words found in the above post: a-e-t-n-d-i-o-s-m-l-u-y-h-c

I did a little test for myself to see the effect of my TC on the 400mm versus what my 75-300 could do. The results are not surprising

Canon 75-300 F/4.0-5.6 EF III USM at 300mm at F/5.6

Canon 400 F/5.6 L

Canon 400 F/5.6 L plus Sigma EX 1.4 TC

In any given situation, I would choose the prime without the 1.4 TC (although the effect isn't too great - I tape the 3 leftmost pins so I still get AF, albeit slow and unreliable). I won't use the zoom unless I have too.

BTW, the test above was done by varying the subject distance to ensure the same image size on the sensor - there was no image manipulation. As before, no sharpening or saturation/hue/contrast manipulation.

I changed from the 100-400 to prime lenses (I initially went for the 300IS and the 135 2. when I changed from a 300D to the 20D. There seemed to be a real problem with this combination with focus - I had many very poor results, much worse than with the 300D.

Having said that, I am much happier with the primes - as has been said, you nearly always use the lens at maximum. I may have been lucky, but don't find dust a major problem despite changing lenses.

I still use a zoom at the lower end (24-70) as that does provide a needed versatility.

Here are two pictures taken with a 300 f/2.8 IS L, one without a converter and one with a converter. The pics were taken from a tripod using a remote release and mirror lockup. No sharpening was applied during conversion from RAW to TIFF. Both pics are 100% crops.

100ISO, 1/5 sec @ f/11. No converter used

100ISO, 1/4 sec @ f/11. Canon 1.4x converter (Type II) used

The loss of sharpness due to the use of the 1.4x converter is very noticable, it's much worse than I'd expected it to be. I'll do some more tests tomorrow using faster shutter speeds.

I think the push pull arangement zoom , is a good idea , very fast to use when in the bush , and out a car window its easier than turning a ring .

I have the sigma 170-500 (Temp solution) and it has a zoom ring , but you can pull the barrlel in and out , which is what I tend to do , as I find it faster and easier while in a vehicle .

If you are only going to want 1 lens with you in the bush , I think that the 100-400 must be a damn good all rounder .
L glass , IS , large zoom range , and a fair price isn't to bad , considering you only compromise a little on the ultra sharpness of the fixed length primes .

Im looking to buy a 400mm f5,6 now , but thats only because I have a host of zoom lenses allready , and I want something to give me crystal clarity .